Scots pine (Pinus sylvestris) leaf. Light micrograph of a section through a needle (leaf) from a Scots pine tree, showing its thick cuticle and thick-walled epidermis (red) and hypodermis (subcutaneous tissue, brown). Stomata (pores) and guard cells can also be seen, along with chloroplasts, and mesophyll tissue composed of parenchyma cells. The vascular tissue is composed of xylem tracheid cells (red) and phloem sieve tube cells (blue). Magnification: x37 when printed 10 centimetres wide.